Open AccessOverproduction of the xylS gene product and activation of the xylDLEGF operon on the TOL plasmid
Author(s) -
Sachiye Inouye,
Atsushi Nakazawa,
Takahiro Nakazawa
Publication year - 1987
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.169.8.3587-3592.1987
Subject(s) - operon , biology , l arabinose operon , plasmid , gene product , gene , inducer , regulator gene , trp operon , pseudomonas putida , regulation of gene expression , microbiology and biotechnology , gene expression , escherichia coli , genetics
The effect of high-level expression of the regulatory gene xylS of the Pseudomonas putida TOL plasmid on the activation of the xylDLEGF operon was investigated in Escherichia coli. The xylS gene was placed downstream from the tac promoter, and the resultant fusion was cloned in cis to the xylDLEGF operon. The expression of the operon was monitored by the level of catechol 2,3-dioxygenase, whose structural gene xylE was placed directly after the operator-promoter region of xylDLEGF. xylS transcription was also determined by reverse transcriptase mapping of mRNA. Overproduction of the xylS gene product elicited constitutive high expression of the xylDLEGF operon even in the absence of the inducer for the operon. The results were consistent with a cascade model for the positive control of the xylDLEGF operon by the xylR and xylS genes (S. Inouye, A. Nakazawa, and T. Nakazawa, Proc. Natl. Acad. Sci. USA, in press): m-xylene, a substrate of the degradative pathway, binds to the xylR gene product; the m-xylene-xylR product complex activates the xylS gene; and the xylS product thus synthesized de novo activates the xylDLEGF operon.